This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A220399 #14 Feb 22 2013 14:40:40
%S A220399 1,0,1,0,2,1,0,3,4,1,0,3,10,6,1,0,0,18,21,8,1,0,-9,21,53,36,10,1,0,
%T A220399 -27,0,99,116,55,12,1,0,-54,-81,117,286,215,78,14,1,0,-81,-270,-27,
%U A220399 528,650,358,105,16,1
%N A220399 A convolution triangle of numbers obtained from A057682.
%C A220399 Triangle T(n,k) given by (0, 2, -1/2, 3/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (1, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938.
%F A220399 G.f.: (1-3*x+3*x^2)/(1-3*x-3*x*y+3*x^2+x^2*y)
%F A220399 G.f for k-th column: ((x-x^2)/(1-3*x+3*x^2))^k.
%F A220399 T(n,k) = 3*T(n-1,k) + T(n-1,k-1) - 3*T(n-2,k) - T(n-2,k-1), T(0,0) = 1, T(1,0) = T(2,0) = 0, T(n,k) = 0 if k<0 or if k>n.
%F A220399 Sum_{k, 0<=k<=n, n>0} T(n,k) = A001792(n-1).
%F A220399 T(n+1,n) = 2*n = A005843(n).
%F A220399 T(n+2,n) = A014105(n).
%F A220399 T(n,1) = A057682(n).
%e A220399 Triangle begins :
%e A220399 1
%e A220399 0, 1
%e A220399 0, 2, 1
%e A220399 0, 3, 4, 1
%e A220399 0, 3, 10, 6, 1
%e A220399 0, 0, 18, 21, 8, 1
%e A220399 0, -9, 21, 53, 36, 10, 1
%e A220399 0, -27, 0, 99, 116, 55, 12, 1
%Y A220399 Cf. A030523, A057682, A104597
%K A220399 sign,tabl
%O A220399 0,5
%A A220399 _Philippe Deléham_, Feb 19 2013